Air control mechanism



Sept. 18, 1962 G. E. VALENTINE ET AL AIR CONTROL MECHANISM Q SEES SE zg 5% a rQEGEEEEGSEEw Filed Aug. 15, 1959 United States Patent 3,054,443 AIR CONTROL MECHANISM George E. Valentine and Joseph H. Eubanlrs, Schuylkill Haven, Pa., assignors to Thermo Dynamics Corporation, a corporation of Pennsylvania Filed Aug. 13, 1959, Ser. No. 833,428 3 Claims. (Cl. 158-28) This invention relates to blower control mechanisms and, more particularly, to improved blower control mechanisms which effect cleaner and more efiicient combustion throughout the firing cycle of oil burners and the like.

In the conventional oil burner system, including a burner, a blower and other associated mechanisms, the air delivery capacity of the blower is usually such that the air delivered to the combustion chamber will be approximately equal to the quantity stoichiometrically required for complete combustion of the fuel when the burner and its environment are at a predetermined optimum operat-,

ing temperature. But while such a design usually promotes efiicient burning throughout the greatest portion of the combustion cycle, it is ineffective to maintain proper combustion conditions at the beginning of each combustion cycle, when the combustion chamber is cold. Under such cold chamber conditions, the quantity of air required to burn a given quantity of fuel efliciently is significantly in excess of that required for efficient burning in a combustion chamber which is substantially at combustion temperature and, unless such excess air is provided, incomplete or dirty combustion will occur with the attendant formation of soot and other undesirable byproducts. In systems in which the oil burner is used to heat a boiler or the like, this problem of soot formation and dirty combustion has posed especially vexing problems, since it has often dictated boiler design on the basis of cleaning ease rather than on efliciency of operation.

Attempted solutions to the problem have taken various forms, none of which has been entirely successful. For example, it has been proposed to increase the air delivery capacity of the blower so as to provide excess air at the beginning of each combustion cycle. But though the delivery of excess air to the cold combustion chamber promotes efiicient and clean burning at the beginning of each combustion cycle, the continued delivery of the excess air throughout the combustion cycle is wasteful and highly inefiicient. The use of variable speed motors to provide the excess air only at the beginning of the combustion cycle but to reduce the blower capacity when the combustion chamber temperature has risen sufiiciently will, of course, eliminate this problem, but only at a prohibitively high cost. Furthermore, mechanical failure of the variable speed control will necessarily result in impairment of proper combustion conditions.

It is accordingly a primary object of this invention to provide an air control mechanism for use in connection with oil burners and the like which will automatically and inexpensively eliminate unclean burning and the attendant formation of sooty combustion by-products at the beginning of each combustion cycle.

Further objects of the instatnt invention are to provide an air control mechanism for use in connection with oil burners and the like:

(1) which inexpensively provides an increase of combustion air to the burner at the beginning of each combustion cycle and which automatically reduces the air flow when the combustion chamber is substantially at the temperature of combustion;

(2) which, when rendered inoperative in the event of a mechanical or other failure, will not interfere with normal combustion conditions in the oil burner; and

(3) which utilizes a solenoid-operated valve mecha- "ice nism operative to leave unrestricted supplementary inlet air ports provided in the blower and to close said supplementary ports in response to a predetermined rise in combustion chamber temperature or to an automatic time control mechanism.

These and other objects of the invention will become apparent as the description proceeds in connection with the accompanying drawings wherein:

FIGURE 1 is a partially sectioned front view of a blower constructed in accordance with the instant invention and showing the position of the solenoid operated valve when it is inoperative to close the supplementary air ports provided in the air inlet member of 'the blower;

FIGURE 2 is a view in partial section taken along line 22 of FIGURE. 1;

FIGURE 3 is a development of the air volume control band used in association with the novel blower mechanism of the instant invention; and

FIGURE 4 is a schematic diagram of a portion ofthe circuit in which the novel air'control mechanism of the instant invention may be used.

Referring to FIGURES 1 and 2 of the drawings, the novel air control mechanism of this invention is shown in conjunction with a conventional squirrel-cage blower 10, which comprises a chamber 12 containing a rotor 14, a motor 16 for driving rotor 14, and the usual tangential outlet section 18 which, through suitable ducting, ultimately communicates with the combustion chamber 19 of the oil burner shown diagrammatically in FIGURE 4.

Projecting outwardly from side wall 20 and surrounding an air inlet aperturre therein (not shown) is a cuplike projection 22 having apertures 23, 25, 26 and 27 in its cylindrical side wall 24. Adjustably mounted about side wall 24 of projection 22 by means of flanges 36 and a bolt 38 is an air volume control band 28 having three groups of apertures 30, 32 and 34. Air volume control band 23 is so designed that when it is secured in place about projection 22 in the manner shown in'FIGURE 1, only the central portion of apertures 30 will be in registry with aperture 25 in side wall 24, the remaining apertures in band 28 being positioned adjacent non-apert-ured portions of said side wall. Since the quantity of apertures 30 is three times as great as the quantity of either apertures 3'2 or 34, control band 28 may be adjusted to expose varying portions of apertures 23, 26 and 27 while leaving aperture 25 fully in registry with a portion of apertures 30 at all times. Prior to operation of the blower, control band 28 should be soadjusted about projection22 that a sufficient portion of apertures '30, 3'2 and34 will be in registry with-apertures 23, '26 and 27 to permit delivery byblower 10 of that quantity of air stoichiometrically necessary to support combustion in the combustion chamber of the oil burner (not shown) when the burner ;and its environment are at normal operating temperature. Combustion under these conditions may be termed normal combustion.

Mounted adjacent aperture 25 by means of bracket 39 is a solenoid 40 having a movable armature 42. Secured to the free end of armature 42 is an arcuate shield 44 having a radius of curvature identical to that of control band 28 and being of a size suflicient to completely cover aperture 25 when pressed against the control band in the extended position of the armature. When the solenoid is not energized, armature 42 will be spring-biased to its extended position, urging arcuate shield 44 against control band 28 and fully covering aperture 25.

As shown in FIGURE 4, the blower motor 16 is connected to a suitable source of power through leads 46 and 48, a normally open thermostatic switch 49 being provided for control of this circuit. Shunted across leads 46 and 48 is a circuit including in series solenoid 40 and a normally 'closed switch 50 which is controlled by a thermostat 52 which is in turn responsive to the'temperature in the oil burner combustion chamber 19. Thermostat 52 isadapted to open switch 50 when the temperature in the ,combustion chamber is sufficiently high to lsupport combustion therein efiiciently and without the f formation of undesirable by-products.

In operation, power is supplied to blower upon audits associated arcuate shield 44 away from control band 28, leaving in unrestricted condition aperture and that portion of apertures in registry therewith.

Since, as aforesaid, control band 28 will be adjusted about projection 22 so that a sufficient portion of apertures 30, 32 and 34 will be in registry with apertures 23,

combustion conditions. Furthermore, if desired, the

solenoid can be energized by means of the ignition and maintained in such energized condition until the ignition period ends. In such a system, of course, the ignition period would have to be extended for a sutficient period of time to leave aperture 25 open until such time as additional air is no longer required to maintain 'eflicient combustion conditions in the combustion chamber.

closingof thermostatic switch 49, which may, if desired,

be made responsive to ambient temperature in a room to be heated. Simultaneously with the starting of blower 10, solenoid 40 will be energized, drawing armature 42 The present embodiment is therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims ratherthan by the foregoing description, and all changes 7 which come within the meaning and range of equivalency 26 and 27 to permit delivery "of that quantity of air 7 stoichiometrically necessary to support combustion in the combustion chamber, the provision at this stage of operation of supplemental air entry port (aperture 25) will I permit the delivery to the combustion chamber of sufficient additional air to assure clean combustion during the starting cycle. This condition will persist until the temperature in the combustion chamber reaches a predetermined point, at which time thermostat 52. will open the 1 normally closed switch 50, de-energizing solenoid 40 and permitting armature 25 and its associated arcuate shield '44to be urged into its normally spring-biassed position against and covering aperture 25 in projection 22.

Inthe foregoing manner, clean and eflicient combustion is achieved not only at the beginning of the combustion cycle, when the combustion chamber is cold,.but, throughout the combustion cycle, even after the temperature in the combustion chamber has risen to the pointwhere no excess air is required. Furthermorqsince the air supplemental inlet (aperture 25) is open only when solenoid 40 is energized, a mechanical or electrical failure which impairs the operation of the solenoid and associated mechanisms will only serve to restore the systerm to conventional operation, in which case only normal air requirements will be satisfied, and Will not impair the operation of the system as a whole or produce dangerous combustion conditions as did numerous prior art devices under similar conditions. 7

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. For example, in lieu of thermostat 52, 1 an automatic timer, of a type Well known in the art, may be used to open switch and to de-energize solenoid 40 at a predetermined time after the start of the combustion cycle corresponding approximately to the time at which a the combustion chamber will have been brought to a temperature at which no additional air is required to support efiicient combustion' In practice, a time of to seconds has been found to be adequate under average of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by United States Letters Patent is:

1. Control mechanism 'for regulating the supply of air to a combustion chamber comprising a blower for delivering air to said combustion chamber, a housing for said blower having an outlet opening and a side inlet opening, a cup-shapedmember rigid with said housing and having -a plurality of peripheral openings, the combined area of said openings being in excess of that necessary to permit delivery by said blower of a sufficient quantity of air to support normal combustion, a band adjustably encircling said opening for regulating the efiective size of said openings, a solenoid carried by said housing having an armature movable radially of said cup-shaped member opposite, certain of said openings, said armature being biased toward said cup-shaped member, an arcuate shield having essentially the same radius as the wall of said cupshaped. member carried by the inner end-of said armature and adapted to normally close. certain of said openings, and control means operative to energize said solenoid to .retract'said armature and said shield to uncover certain of said openings at the beginning of each combustion cycle and to thereafter de-energize said solenoid;

2. The control apparatus according to claim 1 wherein said control means comprises a thermostat responsive to the combustion chamber temperature and operative to de-energize said solenoid When the temperature in said combustion chamberhas risen to a predetermined level.

3. The controlmechanism according to claim 1 wherein said control means comprises a temperature sensitive device etfective to de-energize said solenoid when said i combustion chamber attains a predetermined tempera- 1,503,411 Trumpa Ju1y15, 1952 

